Tapered plasterboards and methods for making them

ABSTRACT

Disclosed herein are plaster boards having a first surface and an opposing second surface, anda first edge and an opposing second edge that bound the first surface and the second surface.The first surface includes a first section and a second section, the first section being raised compared to the second section, the second section abutting the second edge. The second surface includes a first section and a second section that are separated by a boundary between the first edge and the second edge. The first section of the second surface is substantially parallel to the first section of the first surface. The second section of the second surface slopes toward the first surface from the boundary toward the second edge. Methods for making the plaster boards involve forming wet plaster material and drying the wet plaster material such that the wet plaster material hardens into a plasterboard.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority of U.S. ProvisionalPatent Application No. 62/566,381, which is hereby incorporated hereinby reference in its entirety.

BACKGROUND OF THE DISCLOSURE 1. Field of the Disclosure

The present disclosure relates generally to tapered sound dampingplaster boards and methods for making them. The present disclosurerelates more particularly to plaster boards having a first surfacedefined by a first section that is raised compared to a second section,and a second opposing surface that has a sloped or tapered section.

2. Technical Background

A. Tapered Plasterboards

Plaster boards, also known as “drywall boards,” are typically used toconstruct walls within homes, businesses, or other buildings. Plasterboards are very often made of gypsum, but other materials, includinglime and cement, are also used. A typical method for making a plasterboard involves dispensing and spreading a wet plaster material (e.g., aslurry of gypsum in water) onto a paper or fiberglass liner on aplatform, and covering the plaster material with another paper orfiberglass liner. This sandwiched structure is fed through an extruder(e.g., two opposing parallel plates) to provide a structure of a desiredthickness and allowed to cure to form a hardened plaster materialdisposed between the two liners of paper or fiberglass. The plasterboard may be cut into sections having predetermined lengths and widthsthat conform to accepted construction standards.

To form walls having varying dimensions and/or holes that accommodateutility fixtures, it is common to score and snap multiple plasterboardsinto various shapes and sizes and install the plasterboards edge-to-edgesuch that they face wall studs and/or fit around the utility outlets.The wall formed by the plasterboards will generally be moreaesthetically pleasing if the “joints” where the plasterboards contacteach other edge-to-edge are concealed or otherwise not easilydiscernable.

To this end, some plasterboards are formed to have an edge section of afront surface that tapers or slopes inward toward the opposing backsurface of the plasterboard, away from a flat interior section of thefront surface. Generally, such plasterboards will have sections thatslope toward the back surface at two opposing ends. A tapered edgesection may be placed against wall studs next to a tapered edge sectionof another plasterboard. When placed next to each other, the taperedsections of two plasterboards form a slight depression or “v-shaped”region having a small gap where the edges of the respectiveplasterboards meet. The gap is then covered with joint tape and thejoint tape and the depression formed by the two plasterboards is coveredwith joint compound (e.g., “mud” or “joint cement”). The wet jointcompound applied near the joint is smoothed and flattened with a trowel.Subsequently, some of the dried joint compound is abrasively removed(e.g., sanded) from the exposed surfaces of the plasterboards, resultingin a relatively flat and continuous interface between the twoplasterboards.

When non-tapered plasterboards are used, obtaining the flat andcontinuous interface between the two plasterboards becomes moredifficult. For example, it is difficult to apply joint compound to fillthe gap between the plasterboards without at least some of the jointcompound spilling onto the front surface of one or both plasterboards.Generally, any joint compound that spills onto the front surface ofeither non-tapered plasterboard will need to be abrasively removed toyield a flat and continuous interface between the plasterboards. This isbecause any joint compound that remains on the front surface of anon-tapered plasterboard will constitute a protrusion from an otherwisesubstantially flat front surface.

In contrast, wet joint compound can be placed on tapered regions of twoadjacent plasterboards to “fill in” the depression formed by theadjacent tapered regions. A trowel can be used, with a flat interiorsection of the tapered plasterboard as a guide, to smooth the jointcompound to form an interface that is nearly coplanar with the flatinterior surfaces of the adjacent tapered plasterboards. As a result, areduced amount of joint compound may protrude from the flat surface ofthe plasterboards, reducing the time and effort required to abrasivelyremove joint compound to further obscure the gap between the twoplasterboards.

B. Sound Damping Plasterboards

Soundproofing is becoming an ever-increasing concern for theconstruction industry, for example, for use in residences, hotels,schools, and hospitals. Soundproofing is also desirable in theconstruction of theaters and music studios, to insulate noise made inthose areas from surrounding rooms. Model building codes and designguidelines often specify minimum Sound Transmission Class values forwall structures within buildings. While a number of constructiontechniques have been used to address the problem of soundproofing, oneespecially desirable technique uses sound damping plaster boards thatcan be used in place of conventional plaster boards in variousresidential or commercial structures.

A sound damping plaster board typically includes a damping layer havingviscoelastic properties disposed between first and second layers ofhardened plaster material. In some cases, the damping layer may bedisposed between respective paper or fiberglass liners adhered to thefirst and second layers of hardened plaster material. The damping layeris typically more efficient at sound damping than the layers of hardenedplaster material on either side of the damping layer.

C. Tapered Sound Damping Plasterboards

Sound damping plasterboards can also include tapered edge sections. Forexample, a sound damping plasterboard can be formed from a non-taperedplasterboard blank and a tapered plasterboard blank. The non-taperedplasterboard blank and the tapered plasterboard blank initially bothinclude a liner (e.g., paper) on both opposing surfaces that helps holdthe shape of the plasterboard blanks as they dry and harden during theformation process. Subsequently, the liner on what will become the innersurface of each plasterboard blank is abrasively removed (e.g., sanded).Next, the exposed surfaces of the plasterboard blanks are adheredtogether to form a sandwich structure with a viscoelastic polymer oranother sound damping layer between the two plasterboard blanks. Thenon-tapered plasterboard blank forms the back layer of the tapered sounddamping plasterboard and the tapered plasterboard blank forms the frontlayer of the tapered sound damping plasterboard.

However, there are disadvantages to current methods for abrasivelyremoving the liner from the back surface of a tapered plasterboardblank. For example, the abrasive removal process generally involves aroller having an abrasive surface (e.g., sandpaper) spinning and rubbingagainst the back surface of the tapered plasterboard blank as it isconveyed or otherwise passes underneath the roller. As this occurs, theflat interior section of the front surface of the tapered plasterboardblank is supported by the conveyor (or another surface) while taperededge section of the front surface of the tapered plasterboard blank isnot supported. This often causes at least a portion of the tapered edgesection to be forced downward by the roller above, which can cause theplaster material along the edge to break away from the rest of theplaster material. As a result, the finished tapered sound dampingplasterboard might not meet taper specifications or might not include atapered section at all.

Accordingly, what is needed are plasterboards (e.g., plasterboardblanks) that are not as susceptible to breakage caused by an abrasiveroller applying force from above and methods for forming suchplasterboards.

SUMMARY OF THE DISCLOSURE

One aspect of the disclosure is a plasterboard that includes a firstsurface and an opposing second surface, and a first edge and an opposingsecond edge that bound the first surface and the second surface. Thefirst surface includes a first section and a second section, the firstsection is raised compared to the second section, and the second sectionabuts the second edge. The second surface includes a first section and asecond section that are separated by a boundary between the first edgeand the second edge, the first section of the second surface issubstantially parallel to the first section of the first surface, andthe second section of the second surface slopes toward the first surfacefrom the boundary toward the second edge.

Another aspect of the disclosure is a method of forming a plasterboard.The method includes providing wet plaster material having a firstsurface and an opposing second surface. The wet plaster material has afirst edge and an opposing second edge that bound the first surface andthe second surface. The method also includes forming the first surfaceinto a first section and a second section. The first section is raisedcompared to the second section and the second section abuts the secondedge. The method also includes forming the second surface into a firstsection and a second section that are separated by a boundary betweenthe first edge and the second edge. The first section of the secondsurface is substantially parallel to the first section of the firstsurface and the second section of the second surface slopes toward thefirst surface from the boundary toward the second edge. The method alsoincludes drying the wet plaster material such that the wet plastermaterial hardens into a plasterboard.

Additional aspects will be evident from the disclosure herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the methods and devices of the disclosure, and areincorporated in and constitute a part of this specification. Thedrawings are not necessarily to scale, and sizes of various elements maybe distorted for clarity. The drawings illustrate one or moreembodiment(s) of the disclosure, and together with the description serveto explain the principles and operation of the disclosure.

FIG. 1 is a set of two schematic cross-sectional views of a plasterboardbreaking during abrasive removal of a facing layer according to oneembodiment of the disclosure.

FIG. 2 is a set of two schematic cross-sectional views of plasterboardsaccording to another embodiment of the disclosure.

FIG. 3 is a block diagram of a method according to another embodiment ofthe disclosure.

FIG. 4 is a cross-sectional view of wet plaster material being dispensedand formed according to another embodiment of the disclosure.

FIG. 5 is a schematic cross-sectional view of wet plaster material beingformed according to another embodiment of the disclosure.

FIG. 6 is a schematic cross-sectional view of a facing layer of aplasterboard being abrasively removed according to another embodiment ofthe disclosure.

FIG. 7 is a schematic cross-sectional view of a plaster board afterremoval of a facing layer according to another embodiment of thedisclosure.

FIG. 8 is a schematic cross-sectional view of a plaster board afterremoval of a facing layer according to another embodiment of thedisclosure.

FIG. 9 is a schematic cross-sectional view of a tapered sound dampingplasterboard according to another embodiment of the disclosure.

DETAILED DESCRIPTION

As noted above, the present inventors have noted disadvantages oftapered plasterboard blanks and methods for using tapered plasterboardblanks to form tapered sound damping plasterboards. Accordingly, oneaspect of the disclosure is a plasterboard (e.g., hardened plastermaterial) that includes a first surface and an opposing second surface,and a first edge and an opposing second edge that bound the firstsurface and the second surface. The first surface includes a firstsection and a second section and the first section is raised compared tothe second section. The second section of the first surface abuts thesecond edge. The second surface includes a first section and a secondsection that are separated by a boundary between the first edge and thesecond edge. The first section of the second surface is substantiallyparallel to the first section of the first surface, and the secondsection of the second surface slopes toward the first surface from theboundary toward the second edge. The structural features of theplasterboard (e.g., plasterboard blank) noted above can cause thetapered plasterboard blank to be more resistant to breakage duringprocessing to form a tapered sound damping plasterboard, as describedbelow.

In certain embodiments as otherwise described herein, the second sectionof the second surface abuts the second edge.

In certain embodiments as otherwise described herein, the first sectionof the first surface is substantially parallel to the second section ofthe first surface. More specifically, the first section of the firstsurface and the second section of the first surface may be separated bya step-shaped boundary or interface. Such a step-shaped boundary may besubstantially perpendicular to the first section of the first surfaceand/or the second section of the first surface. In other embodiments,the first section of the first surface and the second section of thefirst surface are separated by a sloped boundary.

By the term “substantially” with reference to spatial relationships,amounts, or measurement values described herein, it is meant that therecited characteristic, parameter, or value need not be achievedexactly, but that deviations or variations, including for example,tolerances, measurement error, measurement accuracy limitations andother factors known to those of skill in the art, may occur in amountsthat do not preclude the effect the characteristic was intended toprovide.

In certain embodiments, the first section of the first surface is raisedabove the second section of the first surface by an amount that is atleast 0.01 inches, e.g., at least 0.02 inches or even at least 0.025inches. In certain embodiments, the first section of the first surfaceis raised above the second section of the first surface by an amountthat is no more than 0.2 inches, for example, no more than 0.1 inches,or even no more than 0.05 inches. In certain embodiments, the firstsection of the first surface is raised above the second section of thefirst surface within a range of 0.02 inches to 0.04 inches, within arange of 0.025 inches to 0.035 inches, or within a range of 0.028 inchesto 0.032 inches.

Additionally, in certain embodiments as otherwise described herein, awidth of the second section of the first surface is no more than 12inches, no more than 6 inches, or even no more than 3.5 inches. Forexample, in certain embodiments, the width of the second section of thefirst surface is within a range of 0.5 to 3.5 inches. In this context,the width is defined as spanning between (i) a boundary that separatesthe first section of the first surface and the second section of thefirst surface and (ii) the second edge.

In similar fashion, in certain embodiments as otherwise describedherein, a width of the second section of the second surface is no morethan 12 inches, no more than 6 inches, or even no more than 3.5 inches.For example, in certain embodiments, the width of the second section ofthe second surface is within a range of 0.5 to 3.5 inches. In thiscontext, the width is defined as spanning between (i) the boundary thatseparates the first section of the second surface and the second sectionof the second surface and (ii) the second edge.

In certain embodiments as otherwise described herein, a width of thesecond section of the first surface is no more than 50%, or even no morethan 20% different than the width of the second section of the secondsurface. For example, in certain embodiments as otherwise describedherein, a width of the second section of the first surface issubstantially equal to a width of the second section of the secondsurface. The width of the second section of the first surface spansbetween (i) a boundary that separates the first section of the firstsurface and the second section of the first surface and (ii) the secondedge. The width of the second section of the second surface spansbetween (i) the boundary that separates the first section of the secondsurface and the second section of the second surface and (ii) the secondedge.

But in an alternative embodiment, the width of the second section of thefirst surface is at least twice as large as a width of the secondsection of the second surface. In yet another alternative embodiment,the width of the second section of the second surface is at least twiceas large as the width of the second section of the first surface.

In some embodiments, the first section of the first surface extendsbeyond the boundary that separates the first section of the secondsurface and the second section of the second surface. Or, the secondsection of the first surface may extend beyond the boundary thatseparates the first section of the second surface and the second sectionof the second surface.

Another aspect of the disclosure is a method of forming a plasterboard.The method includes providing (e.g., dispensing onto a conveyor or afacing layer that is on top of a conveyor) wet plaster material having afirst surface and an opposing second surface. The wet plaster materialhas a first edge and an opposing second edge that bound the firstsurface and the second surface. The method further includes forming thefirst surface into a first section and a second section, the firstsection being raised compared to the second section. The second sectionof the first section abuts the second edge. The method further includesforming the second surface into a first section and a second sectionthat are separated by a boundary between the first edge and the secondedge. The first section of the second surface is substantially parallelto the first section of the first surface and the second section of thesecond surface slopes toward the first surface from the boundary towardthe second edge. The method further includes drying the wet plastermaterial such that the wet plaster material hardens into a plasterboard.

In certain embodiments as otherwise described herein, the first surfaceis formed by using a first guide element, such as a bar or flap thathangs down to shape the wet plaster material (e.g., through a linerplaced on the wet plaster material such that the first guide elementpushes against the liner into the wet plaster material to form the firstsurface). More specifically, in certain embodiments the first surfacemay be formed by using a first part of the first guide element to formthe first section of the first surface, and by using a second part ofthe first guide element to form the second section of the first surface.For example, the second part of the first guide element may extendbeyond (e.g., below) the first part of the first guide element towardthe wet plaster material. In certain embodiments, the first part of thefirst guide element and the second part of the first guide element forma step-shaped structure. Additionally, the first part of the first guideelement may include a surface that is substantially parallel to asurface of the second part of the first guide element.

In certain embodiments, the first guide element is used to form thefirst surface such that the first section of the first surface issubstantially parallel to the second section of the first surface (e.g.,by forming a step-shaped boundary that is substantially perpendicular tothe first section of the first surface and the second section of thefirst surface).

The first surface may be formed using the first guide element such thatthe first section of the first surface is raised above the secondsection of the first surface by any amount as described above, e.g., atleast 0.01 inches, or at least 0.02 inches, and/or no more than 0.1inches, e.g., no more than 0.05 inches, for example, within a range of0.02 inches to 0.04 inches, within a range of 0.025 inches to 0.035inches, or within a range of 0.028 inches to 0.032 inches.

The first guide element may also be used to form the first surface suchthat a width of the second section of the first surface is as describedabove, for example, no more than 12 inches, no more than 6 inches, nomore than 4 inches, no more than 3.5 inches, or within a range of 0.5 to3.5 inches. In this context, the width is defined as spanning between(I) a boundary that separates the first section of the first surface andthe second section of the first surface and (ii) the second edge.

In certain embodiments, the second surface may be formed by using asecond guide element. More particularly, the second guide element mayinclude a first part (e.g., a conveyor surface or a platform) used toform the first section of the second surface and a second part (e.g., awedge-shaped shim or a taper belt having a tapered profile) used to formthe second section of the second surface. The second part of the secondguide element may extend beyond (e.g., above) the first part of thesecond guide element toward the wet plaster material. More specifically,the first part of the second guide element may support the wet plastermaterial and the second part of the second guide element may be above orextend above the first part of the second guide element.

The second guide element may be used to form the second surface suchthat a width of the second section of the second surface as describedabove, for example, no more than 12 inches, no more than 6 inches, nomore than 4 inches, no more than 3.5 inches, or within a range of 0.5 to3.5 inches. In this context, the width of the second section of thesecond surface is defined as spanning between (i) the boundary thatseparates the first section of the second surface and the second sectionof the second surface and (ii) the second edge.

In certain embodiments, the first edge of the wet plaster material maybe formed against one or more first edge guide elements, and the secondedge of the wet plaster material may be formed against one or moresecond edge guide elements.

The person of ordinary skill in the art will understand that the use ofguide elements is conventional in the art, and will adapt conventionalguide element techniques for use in the methods described herein.

In some embodiments, the first surface is formed such that the firstsection of the first surface extends beyond the boundary that separatesthe first section of the second surface and the second section of thesecond surface. In other embodiments, the first surface is formed suchthat the second section of the first surface extends beyond the boundarythat separates the first section of the second surface and the secondsection of the second surface.

In particular embodiments, the method includes applying a facing layer(e.g., a paper or fiberglass liner) to the first surface of the wetplaster material, and after drying the wet plaster material such thatthe wet plaster material hardens into the plasterboard, abrasivelyremoving the facing layer and a portion of the plasterboard beneath thefirst section of the first surface of the plasterboard such that thefirst surface becomes substantially flat at the level of the secondsection of the first surface.

In some embodiments, the plasterboard is a first plasterboard (e.g.,plasterboard blank) that is used to form a sound damping plasterboard.In this context, the method may further include applying a viscoelasticpolymer to the substantially flat first surface of the firstplasterboard and/or to a surface of a second plasterboard (e.g.,plasterboard blank), and securing the first plasterboard to the secondplasterboard via the viscoelastic polymer.

One embodiment of a plasterboard (e.g., plasterboard blank) is describedbelow with respect to FIG. 1, which shows two views. The upper portionof FIG. 1 depicts a tapered plasterboard during abrasive removal of afacing layer, such as paper (not shown). The tapered plasterboard issupported by a platform (e.g., a conveyor) from underneath and anabrasive instrument (e.g., a roller) impacts the plasterboard from aboveto abrasively remove (e.g., sand) the facing layer from the top surfaceof the plasterboard. Notably, the tapered underside section of theplasterboard is not supported by the platform. As shown in the bottomportion of FIG. 1, the downward force applied by the abrasive instrumentabove the unsupported tapered underside section may cause theplasterboard to snap undesirably to lose some or all of its taperedsection.

FIG. 2 depicts two embodiments of a plasterboard. The upper portion ofFIG. 2 depicts a plasterboard 200A that may be suitable for processingvia methods described below. The plasterboard 200A includes a facinglayer 470 (e.g., paper) on its surface 202. Other embodiments of theplasterboard include a facing layer on its bottom surface, but such afacing layer is omitted from the upper portion of the FIG. 2 for ease ofillustration.

The lower portion of FIG. 2 depicts a plasterboard 200B that has beenprocessed via methods described below. More specifically, the facinglayer 470 has been removed from the plasterboard 200A and the surface202 has been processed to be substantially flat. The plasterboard 200Bmay be a suitable component of a tapered sound damping plasterboard (seeFIG. 8).

The plasterboard 200A (e.g., hardened plaster material) includes asurface 202 and an opposing surface 204. The plasterboard 200A furtherincludes an edge 206 and an opposing edge 208 that bound the surface 202and the surface 204. The surface 202 includes a section 210, a section212, and a section 213. The section 210 is raised compared to thesection 212 and the section 213. The section 212 abuts the edge 208 andthe section 213 abuts the edge 206. The surface 204 includes a section214 and a section 216 that are separated by a boundary 218 between theedge 206 and the edge 208. The surface 204 also includes a section 217that is separated from the section 214 by a boundary 219 between theedge 206 and the edge 208. The section 214 of the surface 204 issubstantially parallel to the section 210 of the surface 202, and thesection 216 of the surface 204 slopes toward the surface 202 from theboundary 218 toward the edge 208. The section 217 also slopes toward thesurface 202 from the boundary 219 toward the edge 206.

The section 216 abuts the edge 208 and the section 217 abuts the edge206.

As shown in FIG. 2, the section 210 of the surface 202 is substantiallyparallel to the sections 212 and 213 of the surface 202. Additionally,the section 210 and the section 212 are separated by a step-shapedboundary 220. The step-shaped boundary 220 is substantiallyperpendicular to the section 210, the section 212, and the section 213.Additionally, the section 210 and the section 213 are separated by astep-shaped boundary 221. The step-shaped boundary 221 is substantiallyperpendicular to the section 210, the section 212, and the section 213.

In particular embodiments, the section 210 may be raised above thesection 212 and/or the section 213 within a range of 0.02 inches to 0.04inches, within a range of 0.025 inches to 0.035 inches, or within arange of 0.028 inches to 0.032 inches. Other examples are possible.

In certain embodiments, the width of the section 212 is no more than 12inches, no more than 6 inches, no more than 4 inches, no more than 3.5inches, or within a range of 0.5 to 3.5 inches. In this context, thewidth of the section 212 is defined as spanning between the boundary 220and the edge 208 (e.g., along the y-axis).

In certain embodiments, the width of the section 213 is no more than 12inches, no more than 6 inches, no more than 4 inches, no more than 3.5inches, or within a range of 0.5 to 3.5 inches. In this context, thewidth of the section 213 is defined as spanning between the boundary 221and the edge 206 (e.g., along the y-axis).

In some embodiments, the width of the section 216 is no more than 12inches, no more than 6 inches, no more than 4 inches, no more than 3.5inches, or within a range of 0.5 to 3.5 inches. In this context, thewidth of the section 216 is defined as spanning between the boundary 218and the edge 208 (e.g., along the y-axis).

In certain embodiments, the width of the section 217 is no more than 12inches, no more than 6 inches, no more than 4 inches, no more than 3.5inches, or within a range of 0.5 to 3.5 inches. In this context, thewidth of the section 217 is defined as spanning between the boundary 219and the edge 206 (e.g., along the y-axis).

In certain embodiments, the width of the section 212 is no more than 50%different from, no more than 20% different from, or even substantiallyequal to the width of the section 216. In other embodiments, the widthof the section 212 is at least twice as large as, or no more than halfas large as the width of the section 216.

Similarly, in certain embodiments, the width of the section 213 is nomore than 50% different from, no more than 20% different from, or evensubstantially equal to the width of the section 217. In otherembodiments, the width of the section 213 is at least twice as large as,or no more than half as large as the width of the section 217.

In the embodiment of FIG. 2, the boundary 221 is at the same position asthe boundary 219 with respect to the y-axis. Similarly, the boundary 220is at the same position as the boundary 218 with respect to the y-axis.

In other embodiments, the first section of the first surface extendsbeyond the boundary separating the first and second sections of thesecond surface with respect to the y-axis, and the boundary separatingthe first and second sections of the first surface is to the right ofthe boundary separating the first and second sections of the secondsurface.

In yet other embodiments, the second section of the first surfaceextends beyond the boundary that separates the first section of thesecond surface and the second section of the second surface.

As the person of ordinary skill in the art will appreciate, the plasterboards described herein may be made using a variety of differentinorganic base materials. For example, in certain embodiments of theplaster boards and methods as otherwise described herein, the plastermaterial comprises a base material that is a gypsum material. In otherembodiments of the plaster boards and methods as otherwise describedherein, the plaster material comprises a base material that is, forexample, lime or cement. The hardened plaster material may include oneor more fillers or additives in the base plaster material(s), e.g.,fiberglass, a plasticizer material, and/or a foaming agent.

FIG. 3 is a block diagram for a method 300 for forming a plasterboard.For example, the method 300 could be used to form the plasterboards200A, 200B, or 500 of FIG. 2, 6, 7, or 8.

At block 302, the method 300 includes providing wet plaster materialhaving a first surface and an opposing second surface. The wet plastermaterial has a first edge and an opposing second edge that bound thefirst surface and the second surface.

FIG. 4 is a x-z plane view of wet plaster material 400 (e.g., gypsumslurry, cement, and/or lime) being provided (e.g. dispensed). The wetplaster material 400 has a surface 402 and an opposing surface 404. FIG.5, a y-z plane view of the wet plaster material 400, shows that the wetplaster material 400 has an edge 406 and an opposing edge 408 that boundthe surface 402 and the surface 404. The edge 406 is formed against aguide element 469 and the edge 408 is formed against a guide element468. The surface 402 is at least partially covered with the facing layer470 and the surface 404 is at least partially covered with the facinglayer 472.

The wet plaster material 400 is a wet formable body (i.e., includingwater) that can be dried to provide a plaster board (e.g., plasterboards200A or 200B). The person of ordinary skill in the art will appreciatethat a variety of wet plaster materials can be used in the practice ofthe processes as described herein. The wet plaster material can includeany additives or fillers familiar to the person of ordinary skill in theart. The wet plaster material is desirably a semiliquid or otherwiseformable mixture that can be, for example, dispensed and spread onto asurface such as a platform or conveyer.

In some examples, providing the wet plaster material 400 involvesdispensing the wet plaster material 400, via a dispenser 812, onto aplatform 450. The platform 450 may be a stationary platform like a tablein some examples. In other examples, the platform 450 may take the formof a moving conveyor and providing the wet plaster material 400 mayinvolve dispensing the wet plaster material 400 onto the conveyor as theconveyor moves from right to left (e.g., with reference to FIG. 4). Thefacing layer 472 may be disposed on the platform 450, such that the wetplaster material 400 is dispensed on and spread onto the facing layer472. Additionally, the facing layer 470 may be applied to the surface402 of the wet plaster material 400.

At block 304, the method 300 includes forming the first surface into afirst section and a second section, the first section being raisedcompared to the second section. The second section abuts the secondedge. Referring to FIGS. 4 and 5 for example, the surface 402 of the wetplaster material 400 may be formed into sections 410, 412, and 413. Asshown, the section 410 may be raised with respect to the sections 412and 413. The section 412 abuts the edge 408 and the section 417 abutsthe edge 406. In some embodiments, the surface 402 may be formed byusing the guide element 452, which may take the form of one or moreplastic flaps or another solid structure.

The guide element 452 may include a part 454, a part 456, and a part457. The section 410 of the wet plaster material 400 may be formed withthe part 454, the section 412 of the wet plaster material 400 may beformed with the part 456, and the section 413 of the wet plastermaterial 400 may be formed with the part 457. The parts 454, 456, and457 may together form a single flap or solid structure or they may beindependent flaps or structures. As shown, the parts 456 and 457 extendbeyond (e.g., below) the part 454 toward the wet plaster material 400.In particular embodiments, the parts 456 and 457 are c-shaped sheetmetal “shims” that fit over the part 454 (e.g., an extruder plate).Additionally, there may be additional instances of flaps, structures,shims, ironing bars, or edger bars similar to the parts 454, 456, and457 at various locations along the length (e.g., x-axis) of the platform450. As such, the surface 402 may be formed using structures that arelocated at several locations along the length of the platform 450.

The parts 454 and 456 form a step-shaped structure that forms astep-shaped boundary 460 that is substantially perpendicular to thesections 410 and 412. Additionally, the parts 454 and 457 form astep-shaped structure that forms a step-shaped boundary 461 that issubstantially perpendicular to the sections 410 and 413. In this way,the guide element 452 may be used to form the surface 402 such that thesection 410 is substantially parallel to, but raised above, the sections412 and/or 413.

The part 454 includes a surface 462 that is substantially parallel to asurface 464 of the part 456. The surface 462 is also substantiallyparallel to a surface 465 of the part 457. The surface 462 may be raisedwith respect to the surface 465 and/or the surface 464 such that thesection 410 is raised above the section 413 and/or the section 412 by0.02 inches to 0.04 inches, 0.025 inches to 0.035 inches, or 0.028inches to 0.032 inches, for example.

The surface 464 and/or the surface 465 may have respective widths (alongthe y-axis) such that the section 413 and/or the section 412 are formedto have respective widths (along the y-axis) that are no more than 12inches, no more than 6 inches, no more than 4 inches, no more than 3.5inches, or within a range of 0.5 to 3.5 inches.

At block 306, the method 300 includes forming the second surface into afirst section and a second section that are separated by a boundarybetween the first edge and the second edge, the first section of thesecond surface being substantially parallel to the first section of thefirst surface, the second section of the second surface sloping towardthe first surface from the boundary toward the second edge.

Referring to FIG. 5 for example, the surface 404 is formed into asection 414 and a section 416 that are separated by a boundary 418between the edge 406 and the edge 408. The section 414 of the surface404 is substantially parallel to the section 410 of the surface 402.Additionally, the section 416 of the surface 404 slopes toward thesurface 402 from the boundary 418 toward the edge 408, and the section417 of the surface 404 slopes toward the surface 402 from the boundary419 toward the edge 406.

The surface 404 may be formed using a (second) guide element taking theform of the platform 450, a wedge-shaped shim 466 (e.g., an elongatedtaper belt having a tapered profile), and a wedge-shaped shim 467 (e.g.,an elongated taper belt having a tapered profile). The platform 450 maybe used to form the section 414, the wedge-shaped shim 466 may be usedto form the section 416, and the wedge-shaped shim 467 may be used toform the section 417. As shown, the wedge-shaped shims 466 and 467 bothextend beyond (e.g., above) the platform 450 toward the wet plastermaterial 400. More specifically, the wedge-shaped shims 466 and 467 reston top of the platform 450 as the wet plaster material is dispensed ontothe facing layer 472 above the platform 450 and the wedge-shaped shims466 and 467. The wedge-shaped shims 466 and 467 also extend beyond therespective edges 406 and 408 along the y-axis.

The wedge-shaped shim 466 may have a width (along the y-axis) of no morethan 13 inches, no more than 7 inches, or within the range of 1.5 to 4.5inches. Accordingly, the section 416 may have a width (along the y-axis)of no more than 12 inches, no more than 6 inches, or within the range0.5 to 3.5 inches.

The wedge-shaped shim 467 may have a width (along the y-axis) of no morethan 13 inches, no more than 7 inches, or within the range of 1.5 to 4.5inches. Accordingly, the section 417 may have a width (along the y-axis)of no more than 12 inches, no more than 6 inches, or within the range of0.5 to 3.5 inches.

In particular embodiments, the first guide element and the second guideelement (e.g., a platform and wedge-shaped shims) may have shapes andsizes that form the first surface and the second surface such that thefirst section of the first surface extends beyond the boundary thatseparates the first section of the second surface and the second sectionof the second surface. Additionally or alternatively, the first guideelement and the second guide element may have shapes and sizes that formthe first surface and the second surface such that the first section ofthe first surface extends beyond the boundary that separates a thirdsection of the second surface (e.g., a section positioned similar to thesection 417) and the first section of the second surface.

In other embodiments, the first guide element and the second guideelement may have shapes and sizes that form the first surface and thesecond surface such that the second section of the second surfaceextends beyond the boundary that separates the first section of thefirst surface and the second section of the first surface. Additionallyor alternatively, the first guide element and the second guide elementmay have shapes and sizes that form the first surface and the secondsurface such that a third section of the second surface (e.g., a sectionpositioned similar to the section 417) extends beyond the boundary thatseparates a third section of the first surface (e.g., a sectionpositioned similar to the section 413) and the first section of thefirst surface.

At block 308, the method includes drying the wet plaster material suchthat the wet plaster material hardens into a plasterboard. Referring toFIGS. 5 and 6 for example, the wet plaster material 400 is dried to formthe plasterboard 200A. The wet plaster material 400 can be heated (e.g.,via an oven or a radiant heater) and/or generate some of its own heatvia an exothermic reaction. The heat applied or generated during thedrying process is desirably sufficient to cure and harden the wetplaster material 400 to form the plasterboard 200A.

Another aspect of the disclosure relates to a plasterboard (e.g., aplasterboard as described herein) made by a method as described herein.

In a variety of fabrication methods of finished drywall boards, it isdesirable to remove some or all of a facing layer (e.g., a paper orfiberglass liner) disposed on a surface of the board. As describedabove, this is often performed abrasively. The present inventors havedetermined that the tapered plasterboards described herein canadvantageously be less susceptible to breakage when a facing layer isremoved from the first surface of the board. Accordingly, another aspectof the disclosure relates to a method for removing a facing layer from asurface of a plasterboard. The method includes providing a plasterboardas described herein, the plasterboard having a facing layer at its firstsurface; and abrasively removing the facing layer from at least aportion of the first section of the first surface of the plasterboard.

For example, as described above with respect to FIG. 2, facing layer 470may be disposed at the surface 402 of the wet plaster material 400. Inthe embodiment of FIG. 2, there is also a facing layer 472 disposed atthe surface 404 of the wet plaster material 400.

Referring to FIG. 6 as an example, a spinning roller 478 that is coatedwith abrasive material (e.g., sand, diamond, aluminum oxide, or siliconcarbide) may be lowered onto the surface 202 to abrasively remove thefacing layer at least in at least part of the first section of the firstsurface. This can be, for example, performed to re-form the surface 202into a substantially continuous and level surface at the level of thesections 212 and/or 213 (e.g., to arrive at a plasterboard as describedbelow with respect to FIG. 7). In doing so, the facing layer 470 and aportion of the hardened plaster material that forms the section 210 canalso be removed. Once this is done, the plasterboard 200A takes the formof plasterboard 200B shown in FIG. 7. The abrasive removal process canbe performed to yields a substantially flat surface 203 at the firstsurface of the plasterboard. The plasterboard 200B still includes thefacing layer 472 on the surface 204. By performing the abrasive removalprocess discussed above, the result is a tapered plasterboard blankhaving a flat back surface with no facing layer attached. This processmay help avoid breakage of plasterboards during the abrasive removal ofthe facing layer, as described above.

Accordingly, in certain embodiments of the methods as otherwisedescribed herein, the facing layer is substantially removed from thefirst section of the plasterboard. In certain such embodiments, asdescribed above with respect to FIGS. 6 and 7, the facing layer issubstantially removed from the second section of the first surface ofthe plasterboard, for example, to provide a substantially flat firstsurface of the plasterboard.

But in other embodiments, the facing layer is not substantially removedfrom the second section of the first surface of the plasterboard. As theperson of ordinary skill in the art will appreciate based on the presentdisclosure, as the first section of the first surface is raised withrespect to the section of the first surface, the abrasive removalprocess will contact the first section first; accordingly, it ispossible to perform the abrasive removal process to remove the facinglayer in the first section without substantially removing the facinglayer in the second section. In such an embodiment, the process can beperformed so that the abrasive tool does not substantially contact thesecond section of the first surface (or, if there is contact, thecontact has minimal force), such that there is not sufficient force tocreate the danger of breaking the board in the region of the taper. Sucha process can result in a board shown in schematic cross-sectional viewin FIG. 8.

In certain embodiments of the methods as otherwise described herein, theabrasive removal can remove plaster material from the first face of theplasterboard. This can be desirable, e.g., to ensure a surface clean ofliner material to improve adhesion of other materials to the surface.Removal of plaster material can also allow the shaping of the board,e.g., to provide a substantially flat first surface.

Notably, in certain desirable embodiments, during the abrasive removal,substantially less pressure is put on the second section of the firstsurface as compared to the first section of the first surface. This canbe a result of the different heights of the first and second section ofthe first surface, and can advantageously help avoid breakage in theregion of the second section of the second surface. This can be trueeven in cases where the second section of the second surface is notsupported (e.g., by a shim or other structure to counteract any downwardpressure) during the abrasive removal.

Such methods can be advantageously used to make sound-dampeningwallboards. For example, in certain embodiments, the plasterboard is afirst plasterboard, and the method further includes, after the abrasiveremoval, applying a viscoelastic polymer to the first surface of thefirst plasterboard and/or to a surface of a second plasterboard, andsecuring the first surface of the first plasterboard to the secondplasterboard via the viscoelastic polymer.

Referring to FIG. 9, a viscoelastic polymer 474 is applied to either thesurface 203 of the plasterboard 200B or a surface 476 of a plasterboard300, thus forming a tapered sound damping plasterboard 500. A backsurface 480 of the plasterboard 300 (e.g., the tapered sound dampingplasterboard 500) may be placed in a wall space against studs leavingthe tapered surface 204 exposed.

The viscoelastic polymer may include or be filled with a fire resistantmaterial (e.g., zinc borate) and/or a mold resistant material. Invarious embodiments of the plaster boards and methods as describedherein, the viscoelastic polymer may take the form of a viscoelasticpolymer layer or may take the form of a carrier sheet having aviscoelastic polymer disposed thereon. The carrier sheet (whether usedin a damping layer or in a different continuous layer) can be formedfrom a variety of materials, e.g., sheet materials that are capable ofcarrying a viscoelastic polymer. For example, in certain embodiments ofthe plaster boards and methods as described herein, the carrier sheetcomprises (or is) a paper sheet. In other embodiments of the plasterboards and methods as described herein, the carrier sheet comprises (oris) a fiberglass mat or a fiberglass fabric. In other embodiments of theplaster boards and methods as described herein, the carrier sheetcomprises (or is) a woven or non-woven fabric, such as a felt. In otherembodiments of the plaster boards and methods as described herein, thecarrier sheet comprises (or is) a sheet of foamed polymer, e.g., thefoamed polymer sheet sold by BASF under the trade name BASOTECT. Inother embodiments of the plaster boards and methods as described herein,the carrier sheet comprises (or is) a polymer sheet, e.g., a thinpolymer sheet of the type typically used as a plastic release liner foran adhesive, which can be, for example in the range of 0.001-0.002″thick. In other embodiments, the carrier sheet can be an adhesive sheet,e.g., with adhesive such as a pressure-sensitive adhesive presented atone or both surfaces thereof. Such pressure-sensitive adhesive sheetscan be formed from a core sheet (made, e.g., from PVC or PET) withadhesive (e.g., a silicone pressure-sensitive adhesive or a polyacrylateadhesive) disposed on both sides thereof.

The viscoelastic polymer can be disposed on the carrier sheet in varietyof manners. For example, in certain embodiments of the plaster boardsand methods as described herein, the viscoelastic polymer is impregnatedon the carrier sheet (e.g., when the carrier sheet has some level ofporosity). In certain embodiments, the viscoelastic polymer is formed asa layer on one or both sides of the carrier sheet. The viscoelasticpolymer can, for example, be impregnated into the pores of the carriersheet and form layers on either side of the carrier sheet.

As noted above, a variety of viscoelastic polymers can be used in theplaster boards and methods of the disclosure. In various embodiments ofthe plaster boards and methods as described herein, the viscoelasticpolymer is polyvinyl butryal, a silicone, or an acrylic. Theviscoelastic polymer can be a thermally-cured material, e.g., a curedadhesive such as those available under the tradename GreenGlue. Variousviscoelastic glues made by Weber may also be suitable for use.Viscoelastic polymer compositions are also described in U.S. Pat. Nos.8,028,800 and 9,157,241, each of which is hereby incorporated herein byreference in its entirety.

The plasterboards and methods of the disclosure are further described bythe following non-limiting enumerated embodiments, which can be combinedin any logically and technically consistent fashion.

Embodiment 1

A plasterboard comprising:

-   -   a first surface and an opposing second surface, and    -   a first edge and an opposing second edge that bound the first        surface and the second surface,    -   the first surface comprising a first section and a second        section, the first section being raised compared to the second        section, the second section abutting the second edge,    -   the second surface comprising a first section and a second        section that are separated by a boundary between the first edge        and the second edge, the first section of the second surface        being substantially parallel to the first section of the first        surface, the second section of the second surface sloping toward        the first surface from the boundary toward the second edge.

Embodiment 2

The plasterboard of embodiment 1, wherein the second section of thesecond surface abuts the second edge.

Embodiment 3

The plasterboard of any of embodiments 1-2, wherein the plasterboardcomprises hardened plaster material.

Embodiment 4

The plasterboard of any of embodiments 1-3, wherein the first section ofthe first surface is substantially parallel to the second section of thefirst surface.

Embodiment 5

The plasterboard of any of embodiments 1-4, wherein the first section ofthe first surface and the second section of the first surface areseparated by a step-shaped boundary.

Embodiment 6

The plasterboard of embodiment 5, wherein the step-shaped boundary issubstantially perpendicular to the first section of the first surfaceand the second section of the first surface.

Embodiment 7

The plasterboard of any of embodiments 1-4, wherein the first section ofthe first surface and the second section of the first surface areseparated by a sloped boundary.

Embodiment 8

The plasterboard of any of embodiments 1-7, wherein the first section ofthe first surface is raised above the second section of the firstsurface by at least 0.01 inches, e.g., at least 0.02 inches.

Embodiment 9

The plasterboard of any of embodiments 1-8, wherein the first section ofthe first surface is raised above the second section of the firstsurface by no more than 0.1 inches, e.g., no more than 0.05 inches.

Embodiment 10

The plasterboard of any of embodiments 1-9, wherein the first section ofthe first surface is raised above the second section of the firstsurface within a range of 0.02 inches to 0.04 inches.

Embodiment 11

The plasterboard of any of embodiments 1-9, wherein the first section ofthe first surface is raised above the second section of the firstsurface within a range of 0.025 inches to 0.035 inches.

Embodiment 12

The plasterboard of any of embodiments 1-7, wherein the first section ofthe first surface is raised above the second section of the firstsurface within a range of 0.028 inches to 0.032 inches.

Embodiment 13

The plasterboard of any of embodiments 1-12, wherein a width of thesecond section of the first surface is no more than 12 inches, forexample, no more than 6 inches, the width spanning between (i) aboundary that separates the first section of the first surface and thesecond section of the first surface and (ii) the second edge.

Embodiment 14

The plasterboard of any of embodiments 1-12, wherein a width of thesecond section of the first surface is no more than 4 inches, e.g., nomore than 3.5 inches, the width spanning between (i) a boundary thatseparates the first section of the first surface and the second sectionof the first surface and (ii) the second edge.

Embodiment 15

The plasterboard of any of embodiments 1-12, wherein a width of thesecond section of the first surface is within a range of 0.5 to 3.5inches, the width spanning between (i) a boundary that separates thefirst section of the first surface and the second section of the firstsurface and (ii) the second edge.

Embodiment 16

The plasterboard of any of embodiments 1-15, wherein a width of thesecond section of the second surface is no more than 12 inches, e.g., nomore than 6 inches, the width of the second section of the secondsurface spanning between (i) the boundary that separates the firstsection of the second surface and the second section of the secondsurface and (ii) the second edge.

Embodiment 17

The plasterboard of any of embodiments 1-15, wherein a width of thesecond section of the second surface is no more than 4 inches, e.g., nomore than 3.5 inches, the width of the second section of the secondsurface spanning between (i) the boundary that separates the firstsection of the second surface and the second section of the secondsurface and (ii) the second edge.

Embodiment 18

The plasterboard of any of embodiments 1-15, wherein a width of thesecond section of the second surface is within a range of 0.5 to 3.5inches, the width of the second section of the second surface spanningbetween (i) the boundary that separates the first section of the secondsurface and the second section of the second surface and (ii) the secondedge.

Embodiment 19

The plasterboard of any of embodiments 1-18, wherein a width of thesecond section of the first surface is no more than 50% different, e.g.,no more than 20% different, from a width of the second section of thesecond surface,

-   -   wherein the width of the second section of the first surface        spans between (i) a boundary that separates the first section of        the first surface and the second section of the first surface        and (ii) the second edge, and    -   wherein the width of the second section of the second surface        spans between (i) the boundary that separates the first section        of the second surface and the second section of the second        surface and (ii) the second edge.

Embodiment 20

The plasterboard of any of embodiments 1-18, wherein a width of thesecond section of the first surface is substantially equal to a width ofthe second section of the second surface,

-   -   wherein the width of the second section of the first surface        spans between (i) a boundary that separates the first section of        the first surface and the second section of the first surface        and (ii) the second edge, and    -   wherein the width of the second section of the second surface        spans between (i) the boundary that separates the first section        of the second surface and the second section of the second        surface and (ii) the second edge.

Embodiment 21

The plasterboard of any of embodiments 1-18, wherein a width of thesecond section of the first surface is at least twice as large as awidth of the second section of the second surface,

-   -   wherein the width of the second section of the first surface        spans between (i) a boundary that separates the first section of        the first surface and the second section of the first surface        and (ii) the second edge, and    -   wherein the width of the second section of the second surface        spans between (i) the boundary that separates the first section        of the second surface and the second section of the second        surface and (ii) the second edge.

Embodiment 22

The plasterboard of any of embodiments 1-18, wherein a width of thesecond section of the second surface is at least twice as large as awidth of the second section of the first surface,

-   -   wherein the width of the second section of the first surface        spans between (i) a boundary that separates the first section of        the first surface and the second section of the first surface        and (ii) the second edge, and    -   wherein the width of the second section of the second surface        spans between (i) the boundary that separates the first section        of the second surface and the second section of the second        surface and (ii) the second edge.

Embodiment 23

The plasterboard of any of embodiments 1-22, wherein the first sectionof the first surface extends beyond the boundary that separates thefirst section of the second surface and the second section of the secondsurface.

Embodiment 24

The plasterboard of any of embodiments 1-22, wherein the second sectionof the first surface extends beyond the boundary that separates thefirst section of the second surface and the second section of the secondsurface.

Embodiment 25

The plasterboard of any of embodiments 1-24, comprising a facing layerat the first surface of the plasterboard.

Embodiment 26

A method of forming any of the plasterboards of embodiments 1-25, themethod comprising:

-   -   providing wet plaster material having a first surface and an        opposing second surface, the wet plaster material having a first        edge and an opposing second edge that bound the first surface        and the second surface,    -   forming the first surface into a first section and a second        section, the first section being raised compared to the second        section, the second section abutting the second edge,    -   forming the second surface into a first section and a second        section that are separated by a boundary between the first edge        and the second edge, the first section of the second surface        being substantially parallel to the first section of the first        surface, the second section of the second surface sloping toward        the first surface from the boundary toward the second edge, and    -   drying the wet plaster material such that the wet plaster        material hardens into a plasterboard.

Embodiment 27

The method of embodiment 26, wherein providing the wet plaster materialcomprises dispensing the wet plaster material onto a conveyor.

Embodiment 28

The method of embodiment 27, wherein dispensing the wet plaster materialonto a conveyor comprises dispensing the wet plaster material onto afacing layer that is on top of the conveyor.

Embodiment 29

The method of any of embodiments 26-28, wherein forming the firstsurface comprises using a first guide element to form the first surface.

Embodiment 30

The method of embodiment 29, wherein forming the first surfacecomprises:

-   -   using a first part of the first guide element to form the first        section of the first surface,    -   using a second part of the first guide element to form the        second section of the first surface,    -   wherein the second part extends beyond the first part toward the        wet plaster material.

Embodiment 31

The method of embodiment 30, wherein the first part of the first guideelement and the second part of the first guide element form astep-shaped structure.

Embodiment 32

The method of any of embodiments 30-31, wherein the first part of thefirst guide element hangs above the wet plaster material and the secondpart of the first guide element extends below the first part of thefirst guide element.

Embodiment 33

The method of any of embodiments 30-31, wherein the first part of thefirst guide element comprises a surface that is substantially parallelto a surface of the second part of the first guide element.

Embodiment 34

The method of any of embodiments 30-33, wherein forming the firstsurface comprises using the first guide element to form the firstsurface such that the first section of the first surface issubstantially parallel to the second section of the first surface.

Embodiment 35

The method of any of embodiments 30-34, wherein forming the firstsurface comprises using the first guide element to form the firstsurface such that the first section of the first surface and the secondsection of the first surface are separated by a step-shaped boundary.

Embodiment 36

The method of embodiment 35, wherein the step-shaped boundary issubstantially perpendicular to the first section of the first surfaceand the second section of the first surface.

Embodiment 37

The method of any of embodiments 30-36, wherein forming the firstsurface comprises using the first guide element to form the firstsurface such that the first section of the first surface is raised abovethe second section of the first surface by at least 0.01 inches, e.g.,at least 0.02 inches.

Embodiment 38

The method of any of embodiments 30-36, wherein forming the firstsurface comprises using the first guide element to form the firstsurface such that the first section of the first surface is raised abovethe second section of the first surface by no more than 0.1 inches,e.g., no more than 0.05 inches.

Embodiment 39

The method of any of embodiments 30-36, wherein forming the firstsurface comprises using the first guide element to form the firstsurface such that the first section of the first surface is raised abovethe second section of the first surface within a range of 0.02 inches to0.04 inches.

Embodiment 40

The method of any of embodiments 30-36, wherein forming the firstsurface comprises using the first guide element to form the firstsurface such that the first section of the first surface is raised abovethe second section of the first surface within a range of 0.025 inchesto 0.035 inches, e.g., within a range of 0.028 inches to 0.032 inches.

Embodiment 41

The method of any of embodiments 30-40, wherein forming the firstsurface comprises using the first guide element to form the firstsurface such that a width of the second section of the first surface isno more than 12 inches, e.g., no more than 6 inches, the width spanningbetween (i) a boundary that separates the first section of the firstsurface and the second section of the first surface and (ii) the secondedge.

Embodiment 42

The method of any of embodiments 30-40, wherein forming the firstsurface comprises using the first guide element to form the firstsurface such that a width of the second section of the first surface isno more than 4 inches, e.g., no more than 3.5 inches, the width spanningbetween (i) a boundary that separates the first section of the firstsurface and the second section of the first surface and (ii) the secondedge.

Embodiment 43

The method of any of embodiments 30-40, wherein forming the firstsurface comprises using the first guide element to form the firstsurface such that a width of the second section of the first surface iswithin a range of 0.5 to 3.5 inches, the width spanning between (i) aboundary that separates the first section of the first surface and thesecond section of the first surface and (ii) the second edge.

Embodiment 44

The method of any of embodiments 30-43, wherein forming the secondsurface comprises using a second guide element to form the secondsurface.

Embodiment 45

The method of embodiment 44, wherein forming the second surfacecomprises:

-   -   using a first part of the second guide element to form the first        section of the second surface,    -   using a second part of the second guide element to form the        second section of the second surface,    -   wherein the second part of the second guide element extends        beyond the first part of the second guide element toward the wet        plaster material.

Embodiment 46

The method of embodiment 45, wherein the first part of the second guideelement supports the wet plaster material and the second part of thesecond guide element is above the first part of the second guideelement.

Embodiment 47

The method of any of embodiments 45-6 wherein the first part of thesecond guide element comprises a conveyor surface.

Embodiment 48

The method of any of embodiments 45-47, wherein the second part of thesecond guide element comprises a wedge-shaped shim.

Embodiment 49

The method of any of embodiments 45-47, wherein the second part of thesecond guide element comprises a taper belt having a tapered profile.

Embodiment 50

The method of any of embodiments 45-49, wherein forming the secondsurface comprises using the second guide element to form the secondsurface such that a width of the second section of the second surface isno more than 12 inches, e.g., no more than 6 inches, the width of thesecond section of the second surface spanning between (i) the boundarythat separates the first section of the second surface and the secondsection of the second surface and (ii) the second edge.

Embodiment 51

The method of any of embodiments 45-49, wherein forming the secondsurface comprises using the second guide element to form the secondsurface such that a width of the second section of the second surface isno more than 4 inches, e.g., no more than 3.5 inches, the width of thesecond section of the second surface spanning between (i) the boundarythat separates the first section of the second surface and the secondsection of the second surface and (ii) the second edge.

Embodiment 52

The method of any of embodiments 45-49, wherein forming the secondsurface comprises using the second guide element to form the secondsurface such that a width of the second section of the second surface iswithin a range of 0.5 to 3.5 inches, the width of the second section ofthe second surface spanning between (i) the boundary that separates thefirst section of the second surface and the second section of the secondsurface and (ii) the second edge.

Embodiment 53

The method of any of embodiments 26-52, wherein providing the wetplaster material comprises:

-   -   forming the first edge against one or more first edge guide        elements, and    -   forming the second edge against one or more second edge guide        elements.

Embodiment 54

The method of any of embodiments 26-53, wherein forming the firstsurface comprises forming the first surface such that the first sectionof the first surface extends beyond the boundary that separates thefirst section of the second surface and the second section of the secondsurface.

Embodiment 55

The method of any of embodiments 26-54, wherein forming the firstsurface comprises forming the first surface such that the second sectionof the first surface extends beyond the boundary that separates thefirst section of the second surface and the second section of the secondsurface.

Embodiment 56

A plasterboard (e.g., according to any of embodiments 1-25) made by amethod of any of embodiments 26-55.

Embodiment 57

A method for removing a facing layer from a surface of a plasterboard,the method comprising:

-   -   providing a plasterboard according to any of embodiments 1-25        and 56, the plasterboard having a facing layer at its first        surface; and    -   abrasively removing the facing layer from at least a portion of        the first section of the first surface of the plasterboard.

Embodiment 58

The method of embodiment 57, wherein the facing layer is substantiallyremoved from the first section of the first surface of the plasterboard.

Embodiment 59

The method of embodiment 58, wherein the facing layer is substantiallyremoved from the second section of the first surface of theplasterboard, e.g., to provide a substantially flat first surface of theplasterboard.

Embodiment 60

The method of embodiment 58, wherein the facing layer is notsubstantially removed from the second section of the first surface ofthe plasterboard.

Embodiment 61

The method of any of embodiments 57-60, wherein the abrasive removalalso removes plaster material from the first face of the plasterboard.

Embodiment 62

The method of any of embodiments 57-61, wherein during the abrasiveremoval, substantially less pressure is put on the second section of thefirst surface as compared to the first section of the first surface.

Embodiment 63

The method of any of embodiments 57-62, wherein the facing layercomprises paper, fiberglass, and/or thermoplastic.

Embodiment 64

The method of any of embodiments 57-63, wherein the second section ofthe second surface is not supported during the abrasive removal.

Embodiment 65

The method of any of embodiments 57-64, wherein the plasterboard is afirst plasterboard, the method further comprising:

-   -   after the abrasive removal, applying a viscoelastic polymer to        the first surface of the first plasterboard and/or to a surface        of a second plasterboard, and    -   securing the first surface of the first plasterboard to the        second plasterboard via the viscoelastic polymer.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the processes and devicesdescribed here without departing from the scope of the disclosure. Thus,it is intended that the present disclosure cover such modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A plasterboard comprising a body of hardenedplaster and a facing layer disposed at a first surface of theplasterboard, the plasterboard having: a second surface opposing thefirst surface, and a first edge and an opposing second edge that boundthe first surface and the second surface, the first surface comprising afirst section and a second section, the first section being raisedcompared to the second section, the second section abutting the secondedge, the second surface comprising a first section and a second sectiondisposed between the first section and the second edge, the firstsection and the second section being separated by a boundary between thefirst edge and the second edge, the first section of the second surfacebeing substantially parallel to the first section of the first surface,the second section of the second surface sloping toward the firstsurface from the boundary toward the second edge, wherein the facinglayer is not substantially present on the first section of the firstsurface, but is substantially present on the second section of the firstsurface of the plasterboard.
 2. The plasterboard of claim 1, wherein thesecond section of the second surface abuts the second edge.
 3. Theplasterboard of claim 1, wherein the first section of the first surfaceis substantially parallel to the second section of the first surface. 4.The plasterboard of claim 1, wherein the first section of the firstsurface and the second section of the first surface are separated by astep-shaped boundary.
 5. The plasterboard of claim 4, wherein thestep-shaped boundary is substantially perpendicular to the first sectionof the first surface and the second section of the first surface.
 6. Theplasterboard of claim 1, wherein the first section of the first surfaceand the second section of the first surface are separated by a slopedboundary.
 7. The plasterboard of claim 1, wherein the first section ofthe first surface is raised above the second section of the firstsurface by at least 0.02 inches.
 8. The plasterboard of claim 1, whereinthe first section of the first surface is raised above the secondsection of the first surface by no more than 0.1 inches.
 9. Theplasterboard of claim 1, wherein a width of the second section of thefirst surface is no more than 4 inches, the width spanning between (i) aboundary that separates the first section of the first surface and thesecond section of the first surface and (ii) the second edge.
 10. Theplasterboard of claim 1, wherein a width of the second section of thesecond surface is no more than 4 inches, the width of the second sectionof the second surface spanning between (i) the boundary that separatesthe first section of the second surface and the second section of thesecond surface and (ii) the second edge.
 11. The plasterboard of claim1, wherein a width of the second section of the first surface is no morethan 50% different from a width of the second section of the secondsurface, wherein the width of the second section of the first surfacespans between (i) a boundary that separates the first section of thefirst surface and the second section of the first surface and (ii) thesecond edge, and wherein the width of the second section of the secondsurface spans between (i) the boundary that separates the first sectionof the second surface and the second section of the second surface and(ii) the second edge.
 12. The plasterboard of claim 1, wherein a widthof the second section of the first surface is at least twice as large asa width of the second section of the second surface, wherein the widthof the second section of the first surface spans between (i) a boundarythat separates the first section of the first surface and the secondsection of the first surface and (ii) the second edge, and wherein thewidth of the second section of the second surface spans between (i) theboundary that separates the first section of the second surface and thesecond section of the second surface and (ii) the second edge.
 13. Theplasterboard of claim 1, wherein a width of the second section of thesecond surface is at least twice as large as a width of the secondsection of the first surface, wherein the width of the second section ofthe first surface spans between (i) a boundary that separates the firstsection of the first surface and the second section of the first surfaceand (ii) the second edge, and wherein the width of the second section ofthe second surface spans between (i) the boundary that separates thefirst section of the second surface and the second section of the secondsurface and (ii) the second edge.
 14. The plasterboard of claim 1,wherein the first section of the first surface extends beyond theboundary that separates the first section of the second surface and thesecond section of the second surface.
 15. The plasterboard of claim 1,wherein the second section of the first surface extends beyond theboundary that separates the first section of the second surface and thesecond section of the second surface.
 16. A method of forming theplasterboard of claim 1, the method comprising: providing wet plastermaterial having a first surface and an opposing second surface, the wetplaster material having a first edge and an opposing second edge thatbound the first surface and the second surface, forming the firstsurface into a first section and a second section, the first sectionbeing raised compared to the second section, the second section abuttingthe second edge, forming the second surface into a first section and asecond section that are separated by a boundary between the first edgeand the second edge, the first section of the second surface beingsubstantially parallel to the first section of the first surface, thesecond section of the second surface sloping toward the first surfacefrom the boundary toward the second edge, and drying the wet plastermaterial such that the wet plaster material hardens into a plasterboard.17. The method of claim 16, wherein forming the first surface comprises:using a first part of a first guide element to form the first section ofthe first surface, using a second part of the first guide element toform the second section of the first surface, wherein the second partextends beyond the first part toward the wet plaster material.
 18. Amethod for removing a facing layer from a surface of a plasterboard, themethod comprising: providing a plasterboard comprising a body ofhardened plaster and a facing layer disposed at a first surface of theplasterboard, the plasterboard having: a second surface opposing thefirst surface, and a first edge and an opposing second edge that boundthe first surface and the second surface, the first surface comprising afirst section and a second section, the first section being raisedcompared to the second section, the second section abutting the secondedge, the facing layer being disposed on the first section and thesecond section of the first surface, the second surface comprising afirst section and a second section disposed between the first sectionand the second edge, the first section and the second section beingseparated by a boundary between the first edge and the second edge, thefirst section of the second surface being substantially parallel to thefirst section of the first surface, the second section of the secondsurface sloping toward the first surface from the boundary toward thesecond edge; and abrasively removing the facing layer from at least aportion of the first section of the first surface of the plasterboard.19. The method of claim 18, wherein the abrasive removal of the facinglayer is performed without substantially removing the facing layer fromthe second section of the first surface.
 20. The method of claim 18,wherein the abrasive removal also removes hardened plaster material fromthe first surface of the wallboard.
 21. The method of claim 18, whereinduring the abrasive removal, substantially less pressure is put on thesecond section of the first surface as compared to the first section ofthe first surface.
 22. The method of claim 18, further comprising,providing a second plasterboard; after the abrasive removal applying aviscoelastic polymer to at least the first section of the first surfaceof the first plasterboard, to a major surface of the secondplasterboard, or both; and securing the first surface of the firstplasterboard to the major surface of the second plasterboard via theviscoelastic polymer.
 23. A sound-dampening wallboard comprising: afirst plasterboard, wherein the first plasterboard is according to claim1; a second plasterboard having a major surface; and a viscoelasticpolymer securing the first surface of the first plasterboard to themajor surface of the second plasterboard, the viscoelastic polymer beingin contact with at least the first section of the first surface of thefirst plasterboard.
 24. A plasterboard according to claim 1, wherein thefacing layer is formed of paper.